What do Lance Armstrong, Dan Burden, John Eldon and Albert Einstein have in common?

All would agree with Burden's description of the bicycle as "the learning machine." Armstrong, of course, is racing for the Champs-Elysees crown on July 24; Burden is director of Walkable Communities, a Florida-based national organization; Eldon is a digital design engineer in Carlsbad; and Albert Einstein is the guy who came up with the Theory of Relativity – while riding his bike.

"As a child, I suffered from excess weight, severely impaired physical coordination, scoliosis, myopia and shyness," recalls fifty-something Burden. His physical and mental condition began to change, however, when he bought an old balloon-tired Schwinn 2-speed middleweight from a friend for $15. The bike's extended range, he says, "broadened my mind, introduced me to people and took me many places, deep into the Ohio countryside."

The learning machine transported him "to distant places never seen by car, foot or any other means."

It allowed him to learn "the precision skills of well-directed, underhanded tosses of fast-folded papers (while riding no handed) to exact, center porch landings, how to collect money from deadbeat or busy customers, how to accept semi-threatening but friendly teasing of customers in a very different neighborhood than where I lived, such as a beer-drinking cop sitting on his front porch who called my dad (a firefighter) a 'nozzle squeezer.' "

By age 21, Burden was exploring the neighborhoods of Harlem and Bedford-Stuyvesant "with a growing hands-on interest and experience in sociology and geography." Burden later led an Alaska to Argentina bicycle expedition for National Geographic, became an urban planner and emerged as the leader of a national movement to make cities pedestrian-and bicycle-friendly.

As a boy growing up in Los Angeles, John Eldon often cycled 4 miles round-trip to visit one of his local friends. "On the long uphill ride home, I quickly realized that first gear was too low and second gear was too high," he says.

Then came salvation, courtesy of bicycle racer Keith Kingbay who, three years earlier, had convinced Frank Schwinn to introduce the company's first derailleur-geared road bicycles, the Varsity and the Continental.

Soon, Eldon was asking his father for a 10-speed learning machine. "My Christmas present that year, a red, bottom-of-the-line Bianchi, greatly expanded my horizons by enabling me to take 10-to 20-mile rides."

When he entered UCLA, he met other cyclists who had formed the Earth Action Council to promote bicycling and recycling. This, in turn, solidified his decision to pursue his doctoral degree in the newly created Environmental Science and Engineering program. Eldon, now 54, rolled right into the future.

Such testimonials to the brain-pumping power of bicycling stand in sharp contrast to the current silliness and superstition of school boards. Districts these days are prone to dropping recess. Physical education class attendance declined significantly between 1991 and 1995 and has never recovered.

More to the point, as San Diego Union-Tribune staff writer Chris Moran reported in April, "the two-wheeled school commute has virtually disappeared." Some administrators, fearing traffic or strangers, have banned bike-riding to school.

The liberating learning machine has been replaced by the five-block SUV commute and the spine-twisting 40-pound backpack. In a 2002 national survey, 71 percent of adults said they walked or rode a bike to school when they were children; only 22 percent said their children walk or bike to school now.

Meanwhile, the Center for Health and Health Care in Schools at George Washington University reports that schools offering intense physical activity programs "see positive effects on academic achievement, including increased concentration; improved mathematics, reading and writing test scores; and reduced disruptive behavior, even when time for physical education classes reduces the time for academics."

Indeed, when it comes to exercise, Burden, Eldon (and probably Armstrong if he were asked and Einstein if he were alive) want us to think beyond physical health, to mental acuity – and more.

Burden argues passionately that free-range exploration, on foot or by bike, expands our civility, confidence and our humanity. He now helps cities improve their traffic-calming practices, intersection design and other methods of creating or retrofitting communities with the neural pathways we can only reach on foot or by riding a learning machine.

And Eldon, who describes himself as "still your basic klutz," reports his excellent cardiovascular health. He has some of his most creative ideas while biking to work. His midlife crisis gift to himself: a 1981 Bianchi road bike, "which is my healthful, economical alternative to an Italian sports car."

Louv's column appears on Tuesdays. He can be reached via e-mail at rlouv@cts.com or at www.thefuturesedge.com.